How to activate the Bootstrap modal-backdrop?

Question

I want to put up an overlay on my screen while some ajax stuff is running. Building my own overlay div isn\'t a big deal, but, since I\'m already using Bootstrap, I figure

Answer 1

Pretty strange, it should work out of the box as the ".modal-backdrop" class is defined top-level in the css.

Made a small demo: http://jsfiddle.net/PfBnq/